Plankl wrote: a ground cover for tomatoes is needed - this way you will protect the roots...
Here in the Dominican Republic, my problem with tomatoes isn't daytime temperatures, but nighttime temperatures. It is very humid and regularly gets into the upper 80's and into the mid 90's. However, it just doesn't cool off at night, especially here in the city. Apparently nighttime temperatures have to fall below about 80F for pollination to be successful.
I have gotten reasonably good results from the Amish Paste variety. It would yield when others would have beautiful plants but no fruit and the taste is very sweet.